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Rice

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American long-grain rice plants[1]

This article is primarily concerned with rice farming using appropriate technology. For information on rice history, trade, prices, and genetic engineering, please refer to the Wikipedia article on rice There are two methods of growing rice – wet paddy cultivation and upland cultivation. In wet paddy cultivation, the land naturally floods during the rainy season or is lowland covered by water for most of the year. In upland cultivation, land is farmed near dammed rivers or streams for water control.[2]

Program for determining field requirements[edit]

This page is mainly meant as a supplement to the information contained in the document File:Paddy Rice Sizing and Timeline.xls.[2]

Preparing the field[edit]

Water control and flooding[edit]

Controlling water is one of the best ways to improve yields from wet paddy cultivation. Water control allows the field to be flooded and drained when appropriate for planting, early stages of growth, applying manure and fertilizers, and harvesting. [2] For correct water depths when flooding the field during the growth cycle, refer to the document File:Paddy Rice Sizing and Timeline.xls.

Plots and soil preparation[edit]

The field should be divided into plots that are less than 20m by 20m by irrigation channels. The plots should have sufficient slope (~1/200) to ensure that the water will drain well. Build raised dirt paths between plots and ensure that each plot is level. Till and weed soil before planting. Till soil to an average depth of 15cm to help the soil retain water. Level the soil in the plots to ensure that each plant is in the same depth of water. To check your plot, flood it with a bit of water. This will allow you to see places where the soil is too high (humps) or too low (hollows). Following this, go over the field with a leveling board to ensure there are no humps or hollows. Weeds cannot grow when all the soil is submerged. Humps in your field expose it to weed growth, while hollows may prevent proper drainage.[2]

Nursery[edit]

One of the plots in your field should be chosen to grow seeds into seedlings before transplantation. Keeping this nursery close to your home will make it easier to tend to. This nursery should be 10% the size of your rice field.[2] Proper timing an procedure for preparing and planting a nursery can be found in the document File:Paddy Rice Sizing and Timeline.xls.

Choosing and disinfecting seeds[edit]

Choose the best seeds from your previous harvest to plant your next crop. If you have not harvested a rice crop before, local services should have a selection of rice seeds suitable for the climate and conditions.[3] Disinfecting seeds is important to help ensure a healthy crop. Disinfectant procedure and chemical amounts can be found in the document File:Paddy Rice Sizing and Timeline.xls.

Transplanting seedlings[edit]

Seedlings grown in the nursery must be transplanted into very wet soil (the mud in your field should come up to your calf). Cut the tips off the leaves of the seedlings before transplanting. Be sure to plant the seedlings in straight rows with two seedlings in each hole. Planting in rows makes it easier to weed and apply fertilizers.[2] Again, for more information on transplanting, refer to the document File:Paddy Rice Sizing and Timeline.xls.

Crop health[edit]

Weeding should be done frequently to ensure that the rice is fully nourished. Weeds can prevent rice from tillering (developing several stems on the same plant, each stem with its own panicle of rice). Applying fertilizer will help to stop weeds from growing. Cultivating between the rows, either by hand with a hoe or animal-drawn cultivator, will also help improve the rice health. Any weeds that have grown in the rows, however, will have to be pulled out by hand. [2][4]

Manure and fertilizers[edit]

Manure and fertilizer requirements for the nursery and field can be found in the document File:Paddy Rice Sizing and Timeline.xls under the “Paddy Requirements” tab. The proper amounts are calculated from the inputs from your field in the “Paddy Sizing” tab and outputted as a timeline in the “Paddy Rice Timeline” tab.

Harvesting[edit]

Cutting the rice[edit]

Rice should be harvested when it is quite ripe, or when it makes a crunching noise when you bite it. Crops should be upright with a uniform height so that no panicles are drooping. Approximately 85% of the rice heads in the field should be yellow. Rice can be harvested either manually or mechanically. To harvest manually, cut the rice with a sickle either at the stems close to the ground or cut just the panicle. Mechanical harvesting methods include the mechanical reaper, stripper gatherer, Western reaper-combine, Western stripper-combine, Japanese head-feed combine, and Thai-axial flow combine. Rice should not be left on the ground for too long following harvesting. Moisture content of the rice should be between 20 and 25% when it is harvested. [2][4]

Threshing[edit]

Threshing is the process of removing the rice grains from the chaff. This can also be done manually or mechanically. Manual methods include foot threshing, using a threshing rack, or using a flail. Foot threshing involves spreading the rice on a clean mat and trampling with their feet. A flail may also be used in place of trampling to thresh the crop. A threshing rack or Hampasan is a slated wooden or bamboo platform what the rice may be threshed against. Mechanical methods of threshing usually involve a rotating wire-looped drum. The crop may either be thrown into or held close to the rotating machine. [2][4]

Cleaning[edit]

Winnowing is the process of cleaning rice in a sieve, allowing wind to blow away materials other than grain. However, this only removes light, chaffy material. The best way to ensure that your rice crop is clean is to dry it appropriately.[2][4]

Drying[edit]

Drying is the process of reducing moisture content in rice to allow for safe storage. Drying is very important to ensure a quality crop and help prevent losses. Depending on the required storage time, different moisture content is required. For storage of weeks to a few months, the moisture content should be less than 14%. For storage between eight and 12 months, the moisture content should be less than 13%. For storage greater than one year, the moisture content should be less than 9%. However, in drying the rice to 9% moisture content, the rice may encounter a loss of viability. Methods of drying include field drying, sun drying, heated air drying, and in-storage drying. Field drying should be avoided because it greatly reduces the quality of the rice. Sun drying involves spreading the rice on pavement or mats, allowing it to dry in the heat of the sun. Both field drying and sun drying risks creating low quality, dirty rice. Heated air drying and in-storage drying often requires a high capital investment. Fixed batch heated air dryers are the most economical method for drying rice next to field and sun drying. It also creates higher quality, clean rice. [5] For instructions on how to build a fixed batch heated air drying bin from local materials, see Drying mechanism for rice

References[edit]

  1. "Rice". http://en.wikipedia.org/wiki/Rice
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 "Field Guide to Appropriate Technology". Barrett Hazeltine and Christopher Bull, editors. 2003.
  3. ” Rice Knowledge Bank”. International Rice Research Institute. 2009. http://www.knowledgebank.irri.org/rice.htm
  4. 4.0 4.1 4.2 4.3 "Rice Knowledge Bank". International Rice Research Institute. 2009. http://www.knowledgebank.irri.org/rice.htm
  5. "Rice Knowledge Bank". International Rice Research Institute. 2009. http://www.knowledgebank.irri.org/rice.htm

See also[edit]

External links[edit]